As the Americans prepared to drop atomic bombs on the Japanese, the Japanese government was mobilizing the entire population of Japan to impose massive casualties on any Ameircan invasion.
According to the Japanese defensive plan Ketsu-Go, there were now precious few civilians in Japan:
“The defensive plan called for the use of the Civilian Volunteer Corps, a mobilization not of volunteers but of all boys and men 15 to 60 and all girls and women 17 to 40, except for those exempted as unfit. They were trained with hand grenades, swords, sickles, knives, fire hooks, and bamboo spears. These civilians, led by regular forces, were to make extensive use of night infiltration patrols armed with light weapons and demolitions.(43) Also, the Japanese had not prepared, and did not intend to prepare, any plan for the evacuation of civilians or for the declaration of open cities.(44) The southern third of Kyushu had a population of 2,400,000 within the 3,500 square miles included in the Prefectures of Kagoshima and Miyazaki.(45) The defensive plan was to actively defend the few selected beach areas at the beach, and then to mass reserves for an all-out counterattack if the invasion forces succeeded in winning a beachhead.(46)”
The Japanese slogan in 1945:
“The sooner the Americans come, the better…One hundred million die proudly.” was not just for rhetorical effect. Based upon what the Americans had already seen in the Pacific, they could only interpret it literally. American planners for Operation Olympic, the invasion of Kyushu scheduled for November of 1945, were dismayed throughout July of 1945 to learn through intelligence intercepts that the Japanese were piling troops into Kyushu, the Japanese having guessed correctly that Kyushu would be the initial target for any invasion of the Home Islands. Fearing that an invasion would face a one-to-one troop ratio between attackers and defenders, it is possible that if the atomic bombs hadn’t been used, the invasion might have been cancelled, with continuing bombing and naval blockade until the Japanese were starved into submission. If such a strategy had worked, and there was no guarantee of it being successful, it is likely that surrender would have occurred only after several million Japanese had died from famine.